JP2000111597A - Inspection method and repair method for liquid crystal display unit and inspection device of liquid crystal display unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method and repair method making laser repairment possible by specifying the location of a short in signal line with a relatively inexpensive method. SOLUTION: An inspection method for a liquid crystal display unit specifying the location of an electric short generated in signal lines 2 formed in parallel to each other on the liquid crystal display measures a resistance value between signal lines short-circuited to each other, scans the gap between signal lines with a laser light, reads the change in resistance value when the laser light passes on the short-circuited location and specifies the location of the short circuit from the position of laser light scan at the moment the resistance value changes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a defect inspection method and a defect repair method for a liquid crystal display device.

[0002]

2. Description of the Related Art In a liquid crystal display device, a plurality of signal lines running in parallel are formed on a glass substrate. This signal line is formed in the process flow of film formation → photoengraving → etching, but if there is a problem in any of the processes, a “pattern remaining” that bridges the signal line and the signal line occurs. Sometimes. When there is such a "pattern remaining", adjacent signal lines are electrically short-circuited, resulting in a line defect of a liquid crystal display. Therefore, in manufacturing a liquid crystal display device, it is necessary to detect such a defect and repair it.

In a conventional inspection method of a liquid crystal display device, it has been practiced to probe a signal input terminal of each signal line with a probe needle and sequentially measure a resistance value between adjacent signal lines. With this method, it is possible to identify two short-circuited signal lines. However, regardless of where on the signal lines the short-circuit point is located (ie, on the side closer to the signal input terminal or on the side farther from the signal input terminal), the resistance value between the signal lines is the same. Therefore, it is very difficult to specify the location of the short-circuit defect on the signal line.

At present, as a method of repairing a liquid crystal display device, a method of cutting "remaining patterns" using a laser has been established. However, "pattern remains" with laser
In order to cut the
It is necessary to specify with an accuracy of about μm. Therefore, in the method of measuring the resistance value between the signal lines described above, repair by laser cannot be performed, and improvement in the production yield of the liquid crystal display device cannot be expected.

As a test of a liquid crystal display device, a method of measuring various characteristics of each pixel on a completed array substrate (eg, the amount of charge that can be charged and the intensity of an electric field generated around the pixel) has been used. . According to these methods, since the measurement is performed in pixel units, it is sometimes possible to specify the position of the short-circuit point on the signal line. But,
In general, these are very expensive inspection methods, the cost of which has greatly reduced the production costs of liquid crystal displays.

[0006]

As described above, conventional inexpensive methods cannot obtain sufficient information for laser repair, and must rely on expensive inspection methods to obtain sufficient information. SUMMARY OF THE INVENTION In order to avoid such a situation, it is an object of the present invention to provide an inspection method and a repair method in which the location of a short circuit between signal lines is specified by a combination of conventionally existing relatively inexpensive methods and laser repair is possible. Is the purpose.

Further, in the conventional expensive inspection method, pixels on the array substrate must be completed.
Inspection is possible only on completed (or almost complete) array substrates. Therefore, even if the short-circuited portion is characterized by these methods and the laser can be repaired, laser repair may not be possible depending on the location of the short-circuited portion. (For example, when the pattern cannot be cut because the pattern residue exists at a position overlapping the signal line of another layer). In contrast, in the method according to the present invention, since the inspection can be performed immediately after forming the signal line to be repaired, laser repair can be performed smoothly without being affected by interference with other layers.

[0008]

SUMMARY OF THE INVENTION Accordingly, in one aspect of the present invention, a conventional measuring method for measuring the resistance value between signal lines and a conventional laser technique are combined to form a short circuit on a signal line. Suggest a way to locate the location. That is, while monitoring (or observing) the resistance value between two signal lines that are short-circuited with each other, the gap between these signal lines is scanned by a laser. Since the pattern residue causing the short circuit must be somewhere in the gap between the signal lines, the scanned laser will always pass over the pattern residue. At this time, the resistance between the signal lines is instantaneously changed when the laser passes through the pattern residue, because the pattern residue is cut by the laser or the characteristics of that part change due to light irradiation on the pattern residue. Change. At this time,
Locate the defect by referring to the laser scan position.

According to another aspect of the present invention, there is provided an inspection apparatus for a liquid crystal display device including a glass substrate provided with a plurality of signal lines, wherein a resistance for measuring a resistance between the plurality of signal lines is provided. Measuring means, resistance monitoring means for monitoring a change in resistance between the plurality of signal lines, laser light generating means, and defect position specifying means for specifying a laser light scanning position for scanning the laser light Is proposed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is an explanatory diagram of a measuring method according to an embodiment of the present invention. 1 is a glass substrate, 2 is a signal line formed on the glass substrate 1, 3 is a signal input terminal provided at the end of the signal line 2, and 4 is a pattern residue generated between the signal lines. The signal line A1 and the signal line A2 are electrically short-circuited at this portion. A probe unit 5 detects the presence of a short-circuit defect between signal lines. The probe needles B1 and B2 correspond to the signal lines A1 and A2, respectively. 6 and 7 are a constant voltage source and an ammeter for monitoring the resistance value between the signal lines.
For the sake of explanation, those that do not exist independently only between 1 and B2 but also exist for the other probe needles are drawn especially for explanation. Reference numeral 8 denotes a laser, and 9 denotes a mirror for scanning the laser light. The movement of the mirror is precisely controlled so that the laser light correctly moves in the gap between the signal lines.

In this embodiment, a probe unit that collectively probes all signal input terminals is used as a measuring means. Instead of the probe unit, a movable probe block having only a few probe needles is used. It is also possible to use. That is, for example, a probe block having two probe needles is moved to a signal input terminal position corresponding to the signal lines A1 and A2, and probing is performed.

In this case, however, it is necessary to obtain information from somewhere that a pattern remains between A1 and A2. There is another inspection step before the repair step of the present invention,
Therefore, if it is known that a pattern remains between A1 and A2, the method of the movable probe block can be adopted. In this case, the repair device of the present invention can be manufactured at a lower cost than when a probe unit is used.

Next, the operation will be described. First, the probe unit 5 is brought into contact with the signal input terminal 3 to check for a short circuit between the signal lines. In this state, the resistance between the terminals is measured. As a result, it is determined whether or not there is a short circuit between the signal lines. However, this is a conventional inspection. Here, signal lines A1 and A1
Suppose that the existence of a short-circuit defect has been found between them.

Next, a constant voltage is applied between the signal lines A1 and A2, and the value of the flowing current is monitored. Mirror 9 in this state
And scans the laser beam between the signal lines A1 and A2. At this time, the intensity of the laser light is
Under the condition that the signal lines A1 and A2 are not damaged, it is assumed that the signal lines A1 and A2 are set strong enough to cut the remaining pattern. Since the pattern residue 4 causing the short-circuit defect must exist between the signal lines A1 and A2, the scanned laser beam always passes over the pattern residue 4 sometime. Since the laser is set to an intensity capable of cutting the pattern, the pattern remaining 4 is cut at the moment when the laser beam passes over the pattern remaining 4, and the value of the ammeter 7 becomes 0 at that moment. Further, even when the current is not completely cut, the current value becomes small due to the partial cut. The position of the remaining pattern 4 can be specified from the angle of the mirror 9 at this moment.

As a means for controlling the rotation of the mirror 9, a method called a galvanometer (basically the same principle as an ammeter), which is often used in a semiconductor repair device, is used to combine a magnet and a coil. A method of controlling the angle of the magnet by a current flowing through the coil is employed. That is, by attaching the mirror 9 to this magnet, the current of the angle of the mirror is controlled.

Although the remaining pattern 4 is cut by the laser scan, the laser scan speed is high.
The shape of the cut is probably distorted. Thus, the repair is completed by accessing again the pattern remaining 4 whose position has been specified and by the operator cutting again cleanly. Here, as the signal line, a gate line in the TFT, an ITO signal line in the STN, and the like are mainly assumed. Since the formation of these layers occurs relatively early in the LCD manufacturing process, laser repair of detected defects is relatively easy.

When the material of the layer to be repaired is amorphous silicon (a-Si), it is not always necessary to increase the intensity of the laser beam so that the remaining pattern is cut. Since the conductivity of a-Si changes when irradiated with light, the change in current value due to this change may be read. Therefore, only the defect position can be specified without cutting the pattern during laser scanning.

The laser 8 used for scanning is preferably a continuous wave laser. In the case of a pulsed laser, it is necessary to select the number of pulses per unit position according to the scanning speed.

In the first embodiment, since the defect position is specified by laser scanning, very high-speed scanning is possible. However, on the other hand, there is a problem that it is difficult to accurately perform laser scanning on the gap between the signal lines in the range of the size of the liquid crystal display device (typically on the order of several tens of cm).

Embodiment 2 FIG. 2 shows Embodiment 2 as an example for avoiding this problem. Reference numeral 10 denotes a movable stage on which the glass substrate 1 is mounted. In the second embodiment, the laser light source is fixed, and the laser scan is performed relatively by moving the stage. Operations other than this point are exactly the same as those in the first embodiment. In the second embodiment, although not as fast as a laser scan, it can be expected.
Its realization seems to be easy. The reason is,
This is because a stage movement accuracy at a level where the laser is always positioned between the signal lines A1 and A2 is realized.

In the present embodiment, two types of means for moving the stage are used, a means using a ball screw and a means using a linear motor.

Third Embodiment Further, as shown in FIG. 3, a mixture of the first embodiment and the second embodiment can be considered. In other words, it is difficult to accurately perform laser scanning over a long distance, so narrow the range to a feasible distance, and after scanning within that range, move the stage by that distance and then move to the next range Perform a laser scan of. Hereinafter, this operation is repeated. With such a method, both high scan speed and feasibility can be achieved.

In the second embodiment, the laser scan is performed by moving the stage. However, there is a problem that the probe unit must be moved at the same time to keep watching the current value during the scan. Since the probe unit is a unit having a precise configuration, there is a problem in moving the probe unit while probing the substrate.

Fourth Embodiment In a fourth embodiment (FIG. 4), scanning is performed by moving the laser head itself in the direction of the arrow X instead of moving the stage. According to this, the difficulty of mirror control in the first embodiment and the problem of probe unit movement in the second embodiment can be avoided.

[0025]

According to the present invention, short-circuit defects can be inspected / repaired at relatively low cost, which leads to a reduction in manufacturing cost and an improvement in yield.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a measuring method according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a measuring method according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a measuring method according to a third embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a measuring method according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Signal line 3 Signal input terminal 4 Remaining pattern generated between signal lines 5 Probe unit 6 Constant voltage source 7 Ammeter 8 Laser 9 Mirror 10 Stage

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Claims (10)

[Claims] 1. A method for inspecting a liquid crystal display device for identifying the location of an electrical short circuit occurring between signal lines formed in parallel with each other on a liquid crystal display device, comprising: Scan the gap between the signal lines with laser light while measuring the resistance value, read the change in resistance value when the laser light passes over the short-circuit point, and short-circuit from the laser light scan position when the resistance value changes An inspection method that identifies the location of a location. 2. A method for repairing a liquid crystal display device, wherein the location of a short circuit is specified by the inspection method according to claim 1, and the location is accessed again to repair a short circuit defect using a laser beam. 3. The inspection method according to claim 1, wherein the laser beam is reflected by a mirror, and the laser beam is scanned by controlling the angle of the mirror. 4. The inspection method according to claim 1, wherein the laser light source is fixed, and the stage on which the substrate to be inspected is mounted is moved to perform laser scanning relatively. 5. The inspection method according to claim 3, and claim 4.
An inspection method of a liquid crystal display device using the inspection method described above together. 6. The method according to claim 1, wherein the laser scanning is performed by moving the laser light source. 7. An inspection apparatus for a liquid crystal display device including a glass substrate provided with a plurality of signal lines, comprising: a resistance measuring means for measuring a resistance between the plurality of signal lines; An inspection apparatus for a liquid crystal display device, comprising: a resistance value monitoring means for monitoring a change in the resistance value of the liquid crystal, a laser light generation means, and a defect position specifying means for specifying a laser light scanning position for scanning the laser light. 8. An inspection apparatus according to claim 7, wherein said resistance measuring means is a probe unit. 9. An inspection apparatus according to claim 7, wherein said laser beam scanning means comprises a mirror and rotation control means for controlling the rotation of the mirror. 10. The inspection apparatus according to claim 7, wherein the laser beam scanning means is a stage that supports the glass substrate and controls horizontal movement.